The present invention relates to a process for the production of rumen bypass feed supplements. The process converts glyceride oils to their respective fatty acid calcium salts. In particular, the present invention relates to a process for the production of calcium salts of unsaturated fatty acids derived from fish oil. The calcium salts of the present invention, when fed to cattle, provide reproductive benefits, in particular, an increase in fertility as embodied in an increased rate of impregnation. The present invention therefore also relates to methods for providing such benefits in a ruminant.
Dairy cows must be impregnated once a year to maintain a lactation cycle in which milk is produced for ten months at a time with two month rest periods in between during which the cow is dry. Given the gestation period of a dairy cow, the objective is to impregnate the cow within 83 days after calving. The efficient management of a dairy herd thus requires that the cows be maintained at the peak of fertility to ensure re-impregnation within 83 days.
Accordingly, there exists a need for nutritional supplements that promote dairy cow fertility. Fish oil fatty acids have become the focus of numerous research programs that seek to capitalize on their nutritional and physiological properties. WO 99/66877 discloses the use of omega-3 fatty acids of fish oil origin to increase fertility in animals including cattle. Among the omega-3 fatty acids disclosed are eicosapentaenoic acid (EPA) and decosahexaenoic acid (DHA).
Unsaturated fatty acids, however, undergo hydrogenation to saturated fatty acids by microbial action in the rumen and must be fed to ruminants in a protected form. The most familiar form in which fatty acids in general are protected from microbial action in the rumen are the fatty acid calcium salts disclosed by U.S. Pat. Nos. 4,642,317; 4,826,694, 4,853,233; 4,853,233 and 4,909,138. This form of fatty acid protection is widely accepted in the dairy industry.
Fish oils have a glyceride content of 100%. That is, all of the fatty acids in fish oils are in the glyceride form. Fatty acid glycerides do not readily react to form calcium salts using the processes disclosed by the above-listed patents. For a product to be commercially feasible, glyceride levels below about 5 weight percent are desirable to produce a free-flowing and stable product.
U.S. Pat. No. 5,382,678 discloses a process that reportedly can be used to prepare fatty acid calcium salts from feedstocks having glyceride contents as high as 40 weight percent, with the resulting product having a residual glyceride content of less than about 5 weight percent. Products with residual glyceride contents above 5 weight percent lack storage stability, and are susceptible to oxidation, post-heating, melting, subsequent product solidification, and a tendency to form lumps upon storage. Under industrial conditions, however, it has not been possible to consistently obtain residual glyceride levels below 5 weight percent once the initial glyceride content of the fatty acid feed stock is above about 25 weight percent when using the process of U.S. Pat. No. 5,382,678.
Hydrolyzing the glycerides to levels below 25 weight percent is not commercially feasible. Commercial omega-3 fatty acids in the free fatty acid form are so costly as to be commercially unfeasible. One can reduce the glyceride content of the fish oil starting material by blending it with a low glyceride content fatty acid feedstock, such as Palm Fatty Acid Distillate (PFAD), which has a glyceride content of about 15 to 20 weight percent.
However, the quantity of PFAD that would have to be added to fish oil to reduce the glyceride content to levels commercially feasible for use with the process of U.S. Pat. No. 5,382,678 dilutes the concentration of desirable omega-3 fatty acid such as EPA and DHA to ineffective levels. That is, the levels of DHA and EPA in the resulting calcium salt are so low that quantities of calcium salt must be added to the daily feed ration at levels above what is considered acceptable by the dairy industry.
To be commercially viable, omega-3 fatty acid calcium salt feed supplements must have DHA and EPA concentrations high enough to confer the beneficial effects of these omega-3 fatty acids when quantities of the calcium salt are added to feed ration at levels considered acceptable to the cattle industry. Therefore, a need exists for a process by which calcium salts may be prepared from fish oils having high concentrations of omega-3 fatty acid with the calcium salts produced with reduced levels of unreacted glycerides in a free-flowing and stable form easily handled by customers.
This need is met by the present invention. It has now been discovered that fatty acid calcium salts having acceptable levels of residual glycerides can be prepared from high glyceride content starting materials by using elevated levels of calcium oxide, making it possible to prepare fatty acid calcium salts from feedstocks containing levels of fish oil effective to provide useful concentrations of omega-3 fatty acids in the finished product.
Therefore, according to one aspect of the present invention, a method is provided for the preparation of fatty acid calcium salts, which includes the steps of providing a fatty acid feedstock having a glyceride content between about 30 and about 60% by weight; adding to the feedstock from about 2 to about 3 equivalents of calcium oxide relative to the feedstock, so that a reactive admixture is formed; and adding to the reactive admixture from about 2 to about 5 equivalents of water relative to the calcium oxide, so that the calcium oxide hydrates and neutralizes the fatty acids to form calcium salts.
The method of the present invention thus includes the use of feedstocks derived from fish oils diluted to glyceride contents between about 30 and about 60 weight percent with low glyceride content fatty acid feedstocks, such as PFAD. Other suitable sources of low glyceride content fatty acids include fatty acids from soy, cottonseed, corn and other vegetable fatty acid distillates, tallow, yellow grease or other animal or fish derived free fatty acid sources produced by deodorization, refining, hydrolyzation or other processes common in the fats and oil industry.
Thus, the method of the present invention obtains fatty acid calcium salts having useful concentration of omega-3 fatty acids and acceptable levels of residual glycerides that heretofore could not be obtained on a commercial scale using prior art manufacturing techniques. Therefore, according to another aspect of the present invention, fatty acid calcium salts are provided containing omega-3 fatty acids and residual glyceride levels below about 5 weight percent that are prepared by the method of the present invention. More specifically, a fatty acid calcium salt product is provided having a residual glyceride content below about 5 weight percent and containing from about 1 to about 10% by weight of EPA calcium salt and from about 1 to about 10% by weight of DHA calcium salt.
The DHA- and EPA-containing fatty acid calcium salts enhance the fertility of ruminants without using 100% glyceride content fish oil feedstocks. That is, beneficial results are obtained from feedstocks blended with fatty acids from sources other than fish oils.
Therefore, according to still yet another aspect of the present invention, a method is provided for increasing fertility in a ruminant, in which the ruminant is fed an effective amount of the EPA- and DHA-containing fatty acid calcium salts of the present invention. The method of the present invention is particularly effective to enhance the fertility of female ruminants, especially dairy cows. Methods in accordance with the present invention begin feeding the supplements daily to a female ruminant from about 21 days before to about 28 days after parturition and feeding continue at least until conception occurs. The fertility enhancement obtained by the calcium salts of the present invention also includes a reduction in embryonic death in the months following conception. Therefore, methods in accordance with the present invention continue feeding the supplements to a female ruminant for at least 30 days, and preferably for at least 60 days after conception.
The above and other features and advantages of the present invention will become clear from the following description of the preferred embodiment.